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The phenomenon of laser-assisted alpha decay is studied within the framework of non-Hermitian quantum theory integrated with the (t, t ′)-formalism. The width and the lifetime of the alpha cluster of a specific isotope is extracted from the spectrum of the complex-scaled Hamiltonian operator of the nuclear system and estimated numerically. The laser-field-induced correction to the lifetime is computed by first-order (t, t ′)-perturbation calculation with regard to different polarization states and control parameters of the external laser field, adjusting appropriate intensity and photon energy pairs by examining the limit of the non-relativistic approximation of the problem. [ABSTRACT FROM AUTHOR]

We present a specific calculation concerning laser-assisted decaying systems with non-Hermitian spectral calculations merged with the (t,t’)-formalism to estimate the possible intense laser-field-induced corrections to the lifetime of quasi-stationary states. The perturbed complex energy shift caused by the external vector potential which represents the linearly and circularly polarized laser field is calculated in details. This wavefunction-centered method implies the unsuitability of the radiation gauge and length gauge when quasi-stationary states are considered and described within the framework of non-hermitian quantum mechanics since in this case the A2 term cannot be transformed out.

In this paper a wavefunction-centered description of decaying states that are coupled to an external potential of general time-dependence is investigated. We present the application of non-Hermitian spectral calculations merged with the (t, t′)-formalism to estimate the possible time-dependent potential induced corrections to the lifetime of quasi-stationary states. The appliance of the formalism is demonstrated on some specific potential models as illustrative examples that represent decaying systems. We argue, that the presented framework and computational technique might provide a way to evaluate the lifetime of quasi-stationary states of different types of physical decaying systems that are subjected to perturbative, time-dependent drivings. [ABSTRACT FROM AUTHOR]

We present a specific calculation concerning laser-assisted decaying systems with non-Hermitian spectral calculations merged with the (t,t')-formalism to estimate the possible intense laser-field-induced corrections to the lifetime of quasi-stationary states. The perturbed complex energy shift caused by the external vector potential which represents the linearly and circularly polarized laser field is calculated in details. This wavefunction-centered method implies the unsuitability of the radiation gauge and length gauge when quasi-stationary states are considered and described within the framework of non-hermitian quantum mechanics since in this case the A 2 term cannot be transformed out. • Perturbative description of quasi-stationary states in intense laser-fields. • Time-dependent perturbation in the framework of the (tt') formalism. • Resonant states in laser-pulses. [ABSTRACT FROM AUTHOR]

Abstract: The solution of the scattering problem turns out to be a very difficult task both from the formal as well as from the computational point of view. If the last two decades have witnessed decisive progress in ab initio bound state calculations, a rigorous solution of the scattering problem remains limited to the case. Therefore there is a rising interest to apply bound-state-like methods to handle nonrelativistic scattering problems. In this article the latest theoretical developments in this field are reviewed. Five fully rigorous methods will be discussed, which address the problem of nuclear collisions in full extent (including the break-up problem) at the same time avoiding treatment of the complicate boundary conditions or integral kernel singularities. These new developments allow us to use modern bound-state techniques to advance significantly rigorous solution of the scattering problem. [Copyright &y& Elsevier]

In this work, we study the problem in calculation of Stark resonances by using complex absorbing potentials (CAPs), and its solutions. The motivation of using CAPs for calculating Stark resonances stems from the fact that CAPs can be easily inserted to a large variety of available codes for calculating the electronic structure of molecules and atoms. Our conclusion is that the appropriate CAPs for studying ac/dc Stark resonances are those that are associated with smooth‐exterior‐scaling (SES) transformations, which rotate the spatial contour of integration into the complex plane. The performance of SES‐CAPs vs standard commonly used CAPs in different types of basis sets is investigated. [ABSTRACT FROM AUTHOR]